Radio transmitter



Sept. 13, 1932. L. A. HYLAND 'RAbIO TRANSMITTER Filed Jan. 15, 1932INVEI VTOR Hyland Lawrence A;

ATTORNEY Patented Sept. 13, 1932 we; STATES LAWRENCE HYLAND,' OFWASHINGTON, DISTRICT OF COLUMBIA RADIO TRANSMITTER Application filedlanuary 15, 1932. Serial No. 586,909.

(GRANTED UNDER THE ACT'OF'MARCH 3, 1883, AS AMENDED APRIL ZaO, 1928; 370O. G. 757) This invention relates to a radio transmitter and moreparticularly to a radio transmitter for use on board aircraft, in whichan oscillator and one or more stages of radio frequency amplification isused for regular transmission and the oscillator alone, or with alimited number of stages of amplification, is used for emergencytransmission.

Inproviding aircraft communication systerns there is a major problemnvolved 1n assuring emergency commumcation. -At the present time it isthe'practice to use enginedriven generators as the source of power. Inan emergency, when a forced landing 1s necessary, wind-driven generatorsand the engine-driven generators are usually stopped. To effectemergency communication on single engine ships it has been the practiceto include in the aircraft communication equipment a small emergencytransmitter including a hand-operated generator or small batteries; Thisequipment has been limited to extremely small powers and could beoperated for only a short period of time. In many cases no emergencyequipment has been carried whatever, reliance having been placed on themain transmitter during theperiod that the craft was in the air andtrusting that, in the interval between' notification that 39 a landingwas necessaryand the actual land ing, it would be possible to send outvery brief emergency signals; The system .disclosed herein will makeemergency communication with considerable power readily'feasible andsince theequipment used for emergency purposes is an integral part ofthe main equipment, the device will always be ready in the event of anemergency.

The principal object of this invention is 40 to provide anaircraft'radio transmitter nor;

mally fed with the necessary operating potentials by a generator orgenerators driven from the prime mover that drives the craft,

or wind-driven generators with means for 5 supplying necessary operatingpotentials to a portion of the transmitter when the primary generatorsare rendered inoperative.

Another object of this invention is to provide a means for storingenergy derived from the primary generators in such a. form that it maybe utilized to drive the emergency equipment, together with a means forautomatically disconnecting the primary generators from the storingmeans when the pri mary sources become inoperative to produce asufficient potential to charge said storing means.

Other and further objects of this invention will be made apparent fromthe following description and the accompanyig, drawing wherein thesingle figure shows "a schematic circuit diagram of one embodiment ofthis invention.

Referring now to the drawing, reference number 1 denotes a'combinat ionlowrvoltage and high voltage-direct current generator such as isordinarilyemployed on aircraft and which has a common field winding. 2is a voltage regulator of the Terrel' type which provides for thecontrol of'the generator voltage through the action of the con-' tactsincutting a resistance into and out of the field circuit of thegenerator as the voltage changes. 3 is a reverse current relay which isemployed in a low voltage circuit forv connecting the low voltage,winding of the generator 1 tothe storage battery 4 when the generatorhas developed the required'potential. 5 is a dynamotor which is drivenfrom battery 4-and supplies through its high 80 voltage winding thenecessary plate potent1al to operate the eleotron'tube oscillator 6. Anelectron tube amplifier is shown at 7. The filaments of the tube in boththe oscillator andthe amplifier are heated normally from the low voltagewinding 17 of the generator 1. The plate circuit of the, oscillator 6 isfed from the high voltage winding 21 of the dynamotor; 5. The plate cirvcuit of the amplifier 7 is fed from the high voltage winding 15 ofthegenerator 1.

Under normal conditions of operation, that is, when no emergencyexistsfand the armature of generator 1 is being driven at proper speedto generate the required filament and plate potentials, the switch 9. isclosed to position b, in which case the output circuit of the oscillator6 is connected to the input of the amplifier 7 and the output of saidamplifier is connected to the radiating 10o system comprising ground 8and antenna 10.

In this conditionfthe transmitter is operating at its normal output.Assuming now that an emergency exists, in which case the motor .Orother. source of power normally v ope'ratiiig g generator -1 ceases tojfunction, the. reverse current'relay 3 opensa pointin the;circuit 1between thesai'd generatorandbattery {l and dynamotor 5 continues "to bedrix' 'e'n, being supplied with. the 1 necessary operatingv po -ftential fromstora'ge battery 4:, which has been floating across thellow{voltage winding j of generator 1. The high voltage windingtherefore-supplies the 'proper=*potentialfor the plate'circuit of theoscillator 6. switch 9 is then close dto position 'a ,.in which casetheoscillations oftthe oscillator 6 are transmitted by the conductor 11to the antenna lOjfromjwhich they are radiated.

y In the drawing, oscillator '6 is shown in a more or less conventionalform and'it is to be understood that other arrangements employing-thisoscillator circuit or its equivalent togetherwith circuits for keying ormodulatmg with voice frequencies may be used instead, either alone. orin combinat on :with

a stage or stages of amplification before being connected to either the:antenna directly or to the amplifier 7. The amplifier 7 is shown asagsinglel'stage, however, several stages may be used,i'n which case theprincipal of operation pf the system would remain the same.

The voltage regulator 2 which is used.

automatically control the 7 output potentials ofboth the low and -highvoltage windings of generator 1 consists of a relaywinding 12 connectedacross the low voltage terminals of the generator which is adapted toactuate armature 13 to open a path of low resistance in shuntWithresistance 14in the field winding' circuit to reduce'thefieldexcitation as -the potential increases." Obviously anytype of' voltageregulator performing the function of reducing the field excitation withanincrease in the output voltage may beemployed, J

The reverse currentrelay 3 is shown as a relay having two windings, oneof which is connected acrossthe'low voltage leads from f generator 1"and the other of which is connected-in series with the generator 1 and"the battery 4 upon the initial attraction of armature 18 by the firstwinding. Obviously I anytype of reverse current relay, thatwou-ld' Theprehend only the general'vand preferred enibodimentof my invention,andthat various I changes in construction, proportion-and ar rangementof parts may be made within the scope of the? appended claims,jwiithoutsacriicing any ofthe advantages ofmy-lnventlon, V s The herein describedinvention ma be manufactured h and used by orior the Grovern'ment' ofthe United' 'stat'es forgoverir royalty thereon. I

"Icla'iinfi mental purposes without the payment or any 1.In'combinatiomapower-driven'gener ator having 10w potential and highpotential r windings, a storagebattery, means' for con;

necting the low potential winding of said g'e'ncratorfto said batteryresponsive to the generation of a predetermined potential by saidgenerator, adynamotor having ahi'gh voltage winding, means connectingsaid dy-i namotor to be drivenlby said battery,"anf

electron tube oscillator, means'connecting the high voltage winding ofsaid dynamotor'in the plate circuit of saidelectron tube oscilla} tor,means connecting saidbattery in the filament circuitof' said electronftube oscillator,

a radio frequency amplifier, means? connect+ ing' the high voltagewinding ofsaid power driven generator in'the plate'circuit of saidamplifier, means connecting said battery'in the filament circuit'of saidamplifier, a radi- 7 ating system, and means for selectively con- 7necting said radiating system to the output circuit of said amplifier orsaidioscillator whereby said radiating system may be ener-i gized bysaid amplifier when said power driven generator is functioningorby saidoscillator when said generator is not'functioning- 2. In combination, apower-driven genera-- tor having a plurality of output windings,automatic ineansfor regulating the output potential of all. of saidwindings, a storage battery, means for connecting one ofisaid -windingsto'saidbattery responsive to the generation of l a l predetermined"potential thereby, a 'dyna'motor provided with a high voltage output 7winding, an; electron tube oscillator, means for "connecting the output7 winding of said dynamotor in the plate'cireuit of said electron tubeoscillator, an electron tube amplifier,'means for connecting saidbattery to energize the filaments of the tubes in said oscillator and,said amplifier, means for'connecting one of the 'output windings of saidpower-driven generator in the plate circuit of said amplifi'er, aradiating system, means for connecting the output of V said oscillatorto the input of said amplifier,

and means for selectivelyconnecting said am- 7 radiating system to theoutput of said plifier' or said oscillator.

3 In an aircraft radio transmitting system,

a power-driven generator, a battery, a dynamotor, an electron tubeoscillator,an am plifier, means for normally driving said dy namotorcomprising said generator with said battery floating thereac-ross, meansfor driving said dynamotor from said battery and disconnecting'saidgenerator from said 7 battery when said generator is inoperative, meansfor supplying plate potential to said oscillator comprising saiddynamotor, means for supplying plate potential to said amplifiercomprising a high potential Winding of said power-driven generator,means for supplying filament current to said oscillator and saidamplifier comprising the same means as that used to drive saiddynamotor, whereby said oscillator and said amplifier may be energizedWhen said power-driven generator is functioning and said oscillator maybe energized when said power-driven generator'is not functioning.

LAWRENCE A. HYLAND.

